Structural end post unit for railway track

ABSTRACT

A structural end post unit for insulating railway track rails which reduces the insulation medium to a minimum between metallic plates, and fulfills its primary function of becoming a load bearing member of the rail joint.

United States Patent Inventor William R. Hamilton, Jr.

Naperville. Ill.

Appl. No. 811.479

Filed Mar. 28, 1969 Patented July 20, 1971 Assignce Portec, Inc.

Chicago, Ill.

STRUCTURAL END POST UNIT FOR RAILWAY TRACK 5 Claims, 4 Drawing Figs.

u.s. Cl 238/152 Int. Cl E011) 11/00, EOlb ll/32,E0lb26/00 Field of Search 238/150- References Cited UNITED STATES PATENTS Stamos et al Degman Greer 1. Lansing Hamilton, Jr. Cruikshank Primary ExaminerDrayton E. Hoffman Assistant Examiner-Richard A. Bertsch Attorneys-Emory L. Groff and Emory L. Groff, Jr.

ABSTRACT: A structural end post unit for insulating railway track rails which reduces the insulation medium to a minimum between metallic plates, and fulfills its primary function of becoming a load bearing member of the rail joint.

PATENTEU JUL20 I97! F162. FLG. 3. PM.

INVENTOR WlLLIAM R. HAMILTONJR. W W- ORNEY STRUCTURAL END POST UNIT FOR RAILWAY TRACK This invention relates to a specially fabricated structural insulation unit to be placed between the connected ends of rail sections carrying signal current, generally known as end posts, which, in outline. correspond to the cross sectional shape of the adjacent rails.

Since all parts of an insulated rail joint are held together by bolts under tension of great magnitude, end posts are in effect an integral and important part of the load-bearing portion of the track structure because they are subjected to unusual strains and pressures, greater in fact than the rails themselves.

The main cause of the failure of end posts is thermal expansion of welded rail and the very large compression loads that are placed on the end post in compression. In addition to the compression caused thermally, there is an additional load created by the pinching of the rail ends in bending where trains pass over the joints, which has a tendency to crush the head of the end post. Thermal compressive loads as high as 300 tons have been measured on the insulated joint in welded rail territory. Fiber end posts which have been used for years are not capable of standing up under such a load, which averages about 60,000 p.s.i., since fiber only has a strength of approximately 40,000 p.s.i. in this configuration. Much development work has been done in this field with various types of plastic and synthetic materials with the result that materials have been developed to their utmost limits and barely meet the requirements of the imposed loads. The result is that, although the incidence of failure has been drastically reduced, the problem of failure has not been totally eliminated. This problem has traditionally been approached from the standpoint of building an insulator and the potential of this approach has just about been exhausted. The present invention, however, is centered on the premise of building a compressionproof shim to hold the rails apart and also insulate it in the most efficient manner so that it will perform its intended function. Tests so far conducted indicate that this approach provides a satisfactory solution to the problem of end post failure.

Accordingly, it is an object of the present invention to provide an entirely new concept in end post construction, whereby its primary function is as a definite load-bearing member of the insulated joint, capable of absorbing loads of great magnitude imposed thereon without failing. In the present invention the insulating means is reduced to a minimum thickness and yet still complies with maximum standards of design and safety.

The present invention functions not merely as an insulator as end posts have generally come to be known, but it is also a structural member of the insulated joint with emphasis on the structural qualities. By reducing the insulation thickness to a minimum, the compressive strength of the entire unit importantly approaches that of the rail itself. The abrasion from adjoining rail ends is secondary. By way of example it may be noted that thermal stresses of l5,00060,000 p.s.i., bending stresses of 35,000 p.s.i., and misalignment of bolt holes can put loads of 200 --300 tons on the end post in compression.

With the above and other objects in view which will more readily appear as the description proceeds, the invention consists of the parts and materials set forth in the following drawing, in which:

FIG. 1 is a perspective view of the improved end post.

FIG. 2 is a fragmentary elevation.

FIGS. 3 and 4 are detail perspective views of portions of the assembly showing how the entire unit can be wholly or partially provided with an external insulating coating.

Similar reference characters designate corresponding parts in the several figures of the drawing.

As will be observed from the drawing, the end post assembly includes two outer load bearing surfaces 1 and 2 of hard metallic material such as steel, brass or aluminum and a relatively thin intermediate insulating layer 3, preferably of reinforced thermosetting or thermoplastic adhesive, between and bonding together both metallic'layers. As to the bonded area of the reinforcement or the like, the adhesive may include fiberglass, nylon, propylene, dacron, etc.

The above described assembly is then preferably enveloped, as shown at A in FIG. 3, by a coating of polyurethane or its equivalent in the range of IO mils. In some cases it might be sufficient to coat only the edges as shown at B in FIG. 4. Of course. the profile of the entire assembly conforms to the profile of the aligned rail sections.

The uniqueness of the structure described lies in the relation between the thickness of metal and the insulating material. While the end post functions, of course, as an insulator, nevertheless it has the very important. function of being a load bearing portion of the entire track structure. As an insulator, the end post is subject to crushing or scarfing from the rail ends. As a load-bearing member of the track structure, the first consideration is the loads imposed on the assembly, and secondly, its necessary quality as an efficient insulator.

By reducing the thickness of the insulating material to a minimum and securely containing this between the layers of metal, the load bearing or compression quality is greatly increased. To state the matter another way, according to the present invention the end post is first a load bearing portion of the track structure and secondly an insulator.

The thinner the bond line of the insulating layer, the greater the compressive strength of the unit. The metallic members being harder than the insulating material will have greater wearing characteristics against the vertical scrubbing motion 1 of the rail end upon the passage of a train than ordinary hard fiber end posts. By way of example, a preferred ratio of-the thickness of metal to insulation would be five to one, respectively, so that the insulator would comprise a maximum of 20 percent of the thickness of the end post assembly. A satisfactory assembly could be constructed, however, wherein the thickness of the insulation layer would comprise only 3 percent of the total thickness of the end post.

Although an end post according to the invention may conceivably be made by several methods, a preferred method is to form a laminate of a metal sheet, a layer of adhesive insulating material and another metal sheet. The end posts of desired profile are then either saw cut or die cut from the laminate. To

apply the coating of polyurethane or equivalent, if the entire 7 end post is to be coated, it is dipped il'll a solution of the liquid polyurethane or equivalent, the thickness of the coating being controlled by varying the viscosity of the solution. When only the perimeter of the end post is being coated it may be done either by hand by brushing on the solution. If production warrants, the coating may be applied by automated means, for example, by clamping the faces of the end post between two plates and rotating the fixture under a blending machine with a controlled flow of the coating material.

I claim:

1. An insulating end post assembly adapted to be removably inserted between the juxtaposed end faces of railway rails, I

comprising a unitized structural assembly including a pair of platelike outer rail end engaging metallic members having a profile substantially conforming to the profile of the rail ends to be electrically insulated from each other, said metallic members provided with planar faces, a layer of adhesive insulating material disposed between and bonded to the inner opposed faces of said two metallic members to provide a rigid integral assembly, and said adhesive insulating layer is of a thickness no greater than 20 per cent of the total thickness of said end post assembly whereby an insulative assembly is provided having maximum load bearing properties and highly resistant to compressive forces.

2. An insulating end post according to claim 1, wherein the adhesive insulating material is a thermosetting material.

3. An insulating end post according to claim 1, wherein the adhesive insulating material is a thermoplastic material.

4. An insulating end post according to claim 1, wherein the entire external surface thereof is coated with a nonconductive material.

5. An insulating end post according to claim 1, wherein the side edge portions only are coated with a nonconductive material. 

1. An insulating end post assembly adapted to be removably inserted between the juxtaposed end faces of railway rails, comprising a unitized structural assembly including a pair of platelike outer rail end engaging metallic members having a profile substantially conforming to the profile of the rail ends to be electrically insulated from each other, said metallic members provided with planar faces, a layer of adhesive insulating material disposed between and bonded to the inner opposed faces of said two metallic members to provide a rigid integral assembly, and said adhesive insulating layer is of a thickness no greater than 20 per cent of the total thickness of said end post assembly whereby an insulative assembly is provided having maximum load bearing properties and highly resistant to compressive forces.
 2. An insulating end post according to claim 1, wherein the adhesive insulating material is a thermosetting material.
 3. An insulating end post according to claim 1, wherein the adhesive insulating material is a thermoplastic material.
 4. An insulating end post according to claim 1, wherein the entire external surface thereof is coated with a nonconductive material.
 5. An insulating end post according to claim 1, wherein the side edge portions only are coated with a nonconductive material. 